Mutually coupled improved microwave and millimeter wave co-aperture antenna based on electromagnetic bandgap reuse

Abstract

This invention discloses a microwave / millimeter-wave co-aperture antenna with improved mutual coupling based on electromagnetic bandgap multiplexing, specifically relating to the field of microwave / millimeter-wave communication technology. It addresses the shortcomings of existing microwave / millimeter-wave co-aperture antenna designs, which often cannot utilize microwave MIMO technology. Limited adaptable solutions fail to incorporate MIMO applications into co-design considerations, lack solutions for MIMO performance loss caused by mutual coupling, and suffer from limitations in sub-antenna design due to constraints between microwave and millimeter-wave antennas, leading to bandwidth reduction, gain degradation, and beamforming capability deficiencies. The technical solution involves multiplexing millimeter-wave antennas to achieve additional functionality, thereby suppressing mutual coupling between microwave MIMO antennas and enhancing MIMO performance. Furthermore, it enhances the performance of millimeter-wave antennas by multiplexing parts of the microwave antenna structure. This invention enables both dual-band antennas to achieve performance improvements while avoiding performance loss.

Description

Technical Field

[0001] This invention relates to the field of microwave and millimeter-wave communication, and specifically to a microwave and millimeter-wave common-aperture antenna with improved mutual coupling based on electromagnetic bandgap multiplexing. Background Technology

[0002] With the rapid development of the Internet of Things (IoT) era, traditional microwave spectrum resources are insufficient to accommodate dense wireless terminal connections and cannot meet the demand for low latency. Millimeter-wave technology can improve this situation, but its inherent defects, such as high attenuation and weak penetration, mean it cannot independently meet all communication needs. Therefore, microwave and millimeter-wave collaborative networking will be an inevitable trend in future communication technologies. However, for terminal devices, discrete placement of microwave and millimeter-wave antenna arrays will occupy a large amount of internal space, making it difficult to adapt to the trend of smaller and thinner designs. Integrating millimeter-wave antenna arrays and microwave antennas into the same aperture (i.e., achieving a common-aperture antenna) can effectively solve the above dilemma. However, most reported microwave / millimeter-wave common-aperture design schemes cannot apply microwave MIMO technology. In the few designs that integrate microwave MIMO antennas and millimeter-wave antennas, the focus is only on the common-aperture integration concept itself, without explicitly proposing collaborative design requirements for microwave MIMO technology. Therefore, there is a lack of solutions to the problem of MIMO performance loss after common-aperture integration. For example, in multi-element applications, strong mutual coupling can cause changes in the radiation pattern and an increase in the channel bit error rate. In a common-aperture environment, the more complex working environment can exacerbate these problems, degrade microwave antenna performance, and even interfere with antennas in other frequency bands.

[0003] Meanwhile, the problem of "multiple antennas mutually constraining each other" in existing microwave and millimeter-wave co-aperture design schemes cannot be ignored, especially for relatively large microwave antennas, which often face one or more problems such as bandwidth reduction, gain reduction, and profile increase; while millimeter-wave antennas are often constrained by limited layout space, asymmetrical operating environment, and non-independent feed channels, resulting in a loss of beamforming capability. Taking the two mainstream coplanar co-aperture integration schemes as examples: The embedded scheme embeds the millimeter-wave antenna array into the microwave antenna element. In this case, the microwave antenna's radiating structure is significantly disrupted, causing interference or loss of the original radiation mode. The structure reuse scheme usually directly reuses the main structure of the microwave antenna, such as the radiating surface or feed, as the millimeter-wave antenna array. In this case, the millimeter-wave array is severely limited by the microwave antenna structure, and independent feeding of each element is almost impossible, leading to a lack of phased beam scanning capability of the millimeter-wave array.

[0004] Therefore, most existing microwave and millimeter-wave co-aperture antenna designs cannot apply microwave MIMO technology. Among the limited adaptable solutions, MIMO applications are not included in the co-design considerations, and there is a lack of solutions for MIMO performance loss caused by mutual coupling. Furthermore, due to the constraints between microwave and millimeter-wave antenna designs, it is difficult to avoid one or more problems such as bandwidth reduction, gain reduction, and lack of beamforming capability in sub-antennas. Summary of the Invention

[0005] Therefore, this invention solves the problems of existing microwave and millimeter-wave co-aperture antenna designs, which are mostly unable to apply microwave MIMO technology. Limited adaptable solutions do not incorporate MIMO applications into the collaborative design considerations, lack solutions for MIMO performance loss caused by mutual coupling, and, due to the constraints between microwave and millimeter-wave antenna designs, struggle to avoid bandwidth reduction, gain degradation, and beamforming capability loss in sub-antennas. The mutual coupling improvement microwave and millimeter-wave co-aperture antenna based on electromagnetic bandgap multiplexing provided by this invention integrates a microwave MIMO antenna with a phased-beam scanning millimeter-wave antenna under the concept of microwave and millimeter-wave antenna co-aperture integration. Furthermore, by multiplexing millimeter-wave antennas to achieve additional functions, it suppresses mutual coupling between microwave MIMO antennas, thereby enhancing MIMO performance. Further, by multiplexing parts of the microwave antenna structure, it strengthens the performance of the millimeter-wave antenna, enabling both band antennas to achieve performance improvements while avoiding performance loss.

[0006] The present invention provides a microwave and millimeter-wave common aperture antenna based on electromagnetic bandgap multiplexing with improved mutual coupling, comprising a top metal structure, a first dielectric substrate, a metal ground, a second dielectric substrate, and a feed layer metal structure arranged sequentially from top to bottom; the top metal structure includes two rectangular metal patches arranged symmetrically from left to right.

[0007] Furthermore, each of the two rectangular metal patches is provided with a row of grounding holes, a long slot and a power supply probe; the rectangular metal patches are connected to the metal ground through the grounding holes.

[0008] Furthermore, the grounding hole, the elongated slot, and the power supply probe are arranged sequentially from the inside to the outside of the rectangular metal patch.

[0009] Furthermore, the feed probe passes downward through the first dielectric substrate, the metal ground, and the second dielectric substrate, and the bottom of the feed probe is connected to the metal structure of the feed layer.

[0010] Furthermore, a four-element millimeter-wave antenna array is disposed between the two rectangular metal patches.

[0011] Furthermore, each millimeter-wave antenna unit includes two small square metal patches arranged symmetrically front to back. Each small square metal patch has slender metal branches on both sides and a metallized via on each small square metal patch. The small square metal patches are connected to the metal ground through the metallized vias.

[0012] Furthermore, a short groove is provided in the area corresponding to the gap between the two small square metal patches on the metal ground.

[0013] Furthermore, a long slot and a row of evenly distributed grounding holes on the two rectangular metal patches in the top metal structure are excited by signals fed into them through the feed probes at ports one and two, respectively, to form two microwave planar inverted-F antenna elements.

[0014] Furthermore, the four-element millimeter-wave antenna array located in the middle of the top metal structure consists of eight mushroom-shaped structures. Each millimeter-wave antenna array is composed of two mushroom-shaped structures, which are made up of small square metal patches, slender metal branches and metallized vias. After the signals are fed in through independent ports, they are coupled and excited through short slots located in the metal ground.

[0015] Furthermore, the elongated groove has a length of 0.7λ in the vertical direction. g -0.75λ g , λ g The wavelength of the guided wave corresponding to the center frequency of the microwave band is 0.04λ. g -0.06λ g 0.3λ from the grounded edge of the rectangular metal patch. g -0.35λ g In each mushroom-shaped structure, the small square metal patch has a horizontal length of 0.15λ. g -0.2λ g The width is 0.08λ g -0.1λ g The length of the slender metal dendrite is 0.05λ. g -0.07λ g The width is 0.015λ g -0.02λ g The diameter of the metallized via is 0.013λ. g -0.015λ g The spacing between every two mushroom-shaped structures is 0.02λ. g -0.03λ g .

[0016] Furthermore, for this common-aperture antenna structure, in the millimeter-wave band, each pair of mushroom-shaped structures in this invention forms a millimeter-wave antenna element, and the element is excited by a signal fed into the short slot coupling port between two mushroom-shaped structures. This millimeter-wave antenna element operates in the 26.3GHz to 29.8GHz frequency band and has two operating modes: a quasi-TM mode similar to a traditional patch. 01 Matrix and similar traditional surface mount quasi-inverting™ 02 The array consists of four millimeter-wave antenna elements arranged linearly in the vertical direction to form a four-element antenna array. Radiation phase modulation is achieved based on independent feed ports, thus obtaining array beamforming capability. During the operation of the millimeter-wave array, the metal walls of the microwave planar inverted-F antennas located on both sides of the array are reused as surface wave suppression structures, resulting in improved array gain and radiation pattern.

[0017] In the microwave band, the two microwave planar inverted-F antenna elements in this invention are symmetrically arranged in the horizontal direction, each having two operating modes, namely TM. 3 / 2,0 The combination of the two radiation modes—a mode and a radiating slot mode—constitutes the 4.9 GHz microwave band. When a signal is fed into the port of microwave unit one and a matching load is connected to the port of microwave unit two, the signal excites the rectangular metal patch in microwave unit one, forming radiation from microwave unit one. During radiation, microwave unit one's signal is partially coupled to microwave unit two through path coupling, forming mutual coupling between the two units. The weaker this mutual coupling, the smaller the impact on the radiation of unit two itself. When a signal is fed into the port of microwave unit two and a matching load is connected to the port of microwave unit one, the process is the same. During this signal transmission process, the mushroom-shaped structure located between the two microwave units exhibits high impedance characteristics near a specific frequency band, effectively suppressing microwave coupling signals and forming a signal transmission stopband. The frequency band in which this transmission stopband appears can be finely adjusted by controlling the horizontal length of the small rectangular metal patch in the main body of the mushroom-shaped structure and the diameter of the metallized via. Furthermore, by adding slender metal stubs to both sides of the mushroom-shaped structure, the stopband frequency tuning range can be increased by adjusting the length of the slender metal stubs. Simultaneously, since this structure is a high-impedance structure in the vertical direction, changes in its length in the horizontal direction do not affect the vertical operation of the millimeter-wave antenna. Ultimately, the mushroom-shaped structure assembly, i.e., the millimeter-wave antenna array, will significantly improve the mutual coupling of the two-element MIMO planar inverted-F antenna and enhance its radiation performance.

[0018] The technical effects and advantages provided by the present invention in the above technical solution are as follows:

[0019] 1. The present invention provides a microwave and millimeter-wave co-aperture antenna based on electromagnetic bandgap multiplexing and mutual coupling improvement. Based on the design concept of structural multiplexing, in the environment of microwave MIMO antenna and millimeter-wave phased array antenna co-aperture integration, the millimeter-wave antenna is multiplexed as the decoupling electromagnetic bandgap of the microwave antenna, and the microwave antenna is multiplexed as the surface wave suppression structure of the millimeter-wave antenna. This not only avoids the problem of sub-antenna performance degradation that often occurs in traditional co-aperture antenna designs, but also significantly improves the mutual coupling between microwave antenna elements.

[0020] 2. The present invention provides a microwave and millimeter-wave common aperture antenna based on electromagnetic bandgap multiplexing with mutual coupling. The millimeter-wave antenna element consists of a pair of mushroom-shaped structures with slender branches loaded on the sides, which are fed and phase-controlled by slot coupling signals. The four millimeter-wave antenna elements are arranged longitudinally to form a scanning array, and the array operating frequency is controlled by the vertical dimensions of the millimeter-wave element structure.

[0021] 3. The electromagnetic bandgap multiplexing-based mutual coupling improved microwave and millimeter-wave common aperture antenna provided by the present invention uses a millimeter-wave array composed of mushroom-shaped structures as the decoupling electromagnetic bandgap of the microwave antenna. Based on its band-stop characteristics, it suppresses surface wave coupling between microwave antenna elements and introduces mutual coupling nulls into the microwave frequency band. The frequency point where the mutual coupling nulls appear can be controlled by adjusting the horizontal length of the mushroom-shaped structure main patch and the diameter of the central via of the mushroom-shaped structure.

[0022] 4. The electromagnetic bandgap multiplexing-based mutual coupling improved microwave and millimeter-wave common aperture antenna provided by the present invention has slender stubs loaded on the sides of the mushroom-shaped structure group (i.e., millimeter-wave antenna array). These slender stubs exhibit high impedance characteristics in the vertical direction. By adjusting the length of the slender stubs in the horizontal direction, the frequency adjustment range of the mutual coupling null point in the microwave band can be further expanded without affecting the performance of the millimeter-wave antenna.

[0023] 5. The present invention provides a microwave and millimeter-wave common aperture antenna based on electromagnetic bandgap multiplexing with mutual coupling improvement. The microwave MIMO antenna element adopts a planar inverted F antenna type. Two microwave elements are symmetrically arranged in the horizontal direction and are located on both sides of the millimeter-wave array. The metal wall in the element structure constitutes the surface wave suppression structure of the millimeter-wave array, thereby improving the radiation performance of the millimeter-wave antenna array.

[0024] 6. The electromagnetic bandgap multiplexing-based mutual coupling improved microwave and millimeter-wave common aperture antenna provided by the present invention has orthogonal polarization directions of the two antennas, with the millimeter-wave antenna polarized in the vertical direction and the microwave antenna polarized in the horizontal direction. The two antennas have independent feed paths, ensuring excellent isolation between the two frequency ports, and the two antennas can be designed and combined separately.

[0025] 7. The electromagnetic bandgap multiplexing-based mutual coupling improved microwave and millimeter-wave co-aperture antenna provided by this invention not only realizes the integration of microwave MIMO antenna and millimeter-wave phased array antenna, but also overcomes the common problem of "mutual restraint between dual antennas" in existing microwave and millimeter-wave co-aperture antenna designs. It achieves the effects of significantly improving the mutual coupling of microwave MIMO and improving the millimeter-wave gain while obtaining high space utilization. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0027] Figure 1a This is a top view of the overall structure of the antenna of the present invention;

[0028] Figure 1b This is a side view of the overall structure of the antenna of the present invention;

[0029] Figure 1c This is a top view of a single element in the millimeter-wave antenna array of the present invention;

[0030] Figure 2 The microwave band reflection coefficient diagram of the mutual coupling improved microwave / millimeter wave co-aperture antenna based on electromagnetic bandgap multiplexing of this invention is shown.

[0031] Figure 3 a is the radiation pattern of the microwave / millimeter-wave common-aperture antenna with improved mutual coupling based on electromagnetic bandgap multiplexing in the microwave band at the first resonant frequency.

[0032] Figure 3 b is the radiation pattern of the microwave / millimeter-wave common-aperture antenna with improved mutual coupling based on electromagnetic bandgap multiplexing in the microwave band at the second resonant frequency.

[0033] Figure 4 The diagram shows the port reflection coefficient and array gain of the millimeter-wave band common-aperture antenna based on electromagnetic bandgap multiplexing and mutual coupling improvement according to this invention.

[0034] Figure 5 The radiation pattern of the millimeter-wave array of the microwave / millimeter-wave co-aperture antenna based on electromagnetic bandgap multiplexing with improved mutual coupling is shown in this invention at 28 GHz.

[0035] Figure 6 This is a horizontal beam scan diagram of the millimeter-wave array of the microwave / millimeter-wave common-aperture antenna based on electromagnetic bandgap multiplexing improved by mutual coupling according to the present invention.

[0036] Figure 7This is a diagram showing the port isolation of the dual-band microwave / millimeter-wave common-aperture antenna based on electromagnetic bandgap multiplexing, as described in this invention.

[0037] Explanation of reference numerals in the attached figures:

[0038] 1. Top layer metal structure; 1-1. Rectangular metal patch; 1-2. Long strip slot; 1-3. Grounding hole; 1-4. Feed probe; 1-5. Four-element millimeter-wave antenna array; 1-5-1. Small square metal patch; 1-5-2. Slender metal branch; 1-5-3. Metallized via; 2. First dielectric substrate; 3. Metal ground; 3-1. Short slot; 4. Second dielectric substrate; 5. Feed layer metal structure. Detailed Implementation

[0039] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0040] This invention provides a microwave / millimeter-wave common-aperture antenna with improved mutual coupling based on electromagnetic bandgap multiplexing, as shown in Figure 1. It mainly consists of a top metal structure 1, a first dielectric substrate 2, a metal ground plane 3, a second dielectric substrate 4, and a feed layer metal structure 5. The feed layer metal structure 5 has port one, an independent port, and port two as shown in Figure 1. Each of the two rectangular metal patches 1-1 in the top metal structure 1 has a long slot 1-2 and a row of evenly distributed grounding holes 1-3. These are excited by signals fed into port one and port two via feed probes 1-4, respectively, forming two microwave planar inverted-F antenna elements, namely microwave element one and microwave element two in Figure 1. Eight mushroom-shaped structures located in the middle of the top-layer metal structure 1 form a four-element millimeter-wave antenna array 1-5. Each millimeter-wave antenna element consists of two mushroom-shaped structures (constructed from small square metal patches 1-5-1, slender metal branches 1-5-2, and metallized vias 1-5-3). Signals are fed into each structure via independent ports and then coupled and excited through short slots located in the metal ground 3. In this common-aperture antenna, the elongated slot 1-2 has a vertical length of 0.7λ. g -0.75λ g (λ g (Wavelength corresponding to the center frequency of the microwave band), with a width of 0.04λ. g -0.06λ g The distance from the grounding edge of the rectangular metal patch 1-1 is 0.3λ. g -0.35λ g In each mushroom-shaped structure, the small square metal patch 1-5-1 has a horizontal length of 0.15λ. g -0.2λ g The width is 0.08λ g -0.1λg The slender metal dendrite 1-5-2 has a length of 0.05λ. g -0.07λ g The width is 0.015λ g -0.02λ g The diameter of the metallized via 1-5-3 is 0.013λ. g -0.015λ g The spacing between every two mushroom-shaped structures is 0.02λ. g -0.03λ g .

[0041] Based on the above analysis of the working mechanism and design guidance, this invention provides a case study for reference. The structure of this electromagnetic bandgap multiplexing-based mutually coupled improved microwave / millimeter-wave common-aperture antenna is shown in Figure 1. In the design case, the first dielectric substrate 2 uses F4B substrate, and the second dielectric substrate 4 uses R04003C substrate. The simulation results of the matching and gain of the proposed common-aperture antenna in the microwave band are as follows: Figure 2 As shown, the 10-dB impedance matching bandwidth in the microwave band is 6.2%, covering 4.79GHz to 5.1GHz. Within the entire band, the mutual coupling level between the two elements is less than -18.2dB; while without an electromagnetic bandgap, i.e., a millimeter-wave antenna, the mutual coupling at the center frequency will be as high as -9.8dB. Figure 3 Simulated radiation patterns of the microwave antenna at two resonant frequencies in this case study are shown. To clearly demonstrate the impact of decoupling on the radiation pattern, the microwave antenna without a millimeter-wave antenna (i.e., in a non-co-aperture environment) is also simulated in this case study. After decoupling, the radiation pattern shift of the planar inverted-F antenna is improved to some extent, achieving better spatial coverage, and cross-polarization is also significantly reduced. These results demonstrate that the co-aperture antenna design achieves a significant improvement in microwave mutual coupling.

[0042] In this case, the simulation results of the independent port reflection coefficient and array gain of the common-aperture antenna in the millimeter-wave band are as follows: Figure 4 As shown. The millimeter-wave band bandwidth ranges from 25.9 GHz to 29.8 GHz, which meets the requirements for applications operating in the n257 band (i.e., 26.5 GHz to 29.5 GHz). The inter-element mutual coupling is less than -17 dB, and the antenna array gain within the band is greater than 10.5 dB, demonstrating good array performance.

[0043] Figure 5 The radiation pattern of the millimeter-wave antenna array at its center frequency (28 GHz) is shown. The antenna's radiation pattern is symmetrical, and the cross-polarization level is less than -25 dB. Furthermore, by independently feeding the millimeter-wave antenna elements and adjusting the feed phase difference, the millimeter-wave array can achieve beam scanning. Figure 6 As shown, the millimeter-wave antenna array in this case can support beam scanning of ±40°.

[0044] Figure 7 The simulation results show the isolation between the microwave band feed port and the millimeter-wave band port of the common-aperture antenna in this case. In the microwave band, the isolation between the two band ports is greater than 50dB, and in the millimeter-wave band, the isolation between the two band ports is greater than 33dB. The relevant results indicate that the microwave antenna and the millimeter-wave array operate independently and the radiated interference is weak.

[0045] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A microwave / millimeter-wave common-aperture antenna with improved mutual coupling based on electromagnetic bandgap multiplexing, characterized in that, It includes a top metal structure (1), a first dielectric substrate (2), a metal ground (3), a second dielectric substrate (4), and a feed layer metal structure (5) arranged from top to bottom; the top metal structure includes two rectangular metal patches (1-1) arranged symmetrically on the left and right, and a four-element millimeter-wave antenna array (1-5) arranged between the two rectangular metal patches (1-1); Both rectangular metal patches (1-1) are provided with a row of grounding holes (1-3), a long strip groove (1-2), and a power supply probe (1-4); Each millimeter-wave antenna unit includes two small square metal patches (1-5-1) arranged symmetrically front to back. Each small square metal patch (1-5-1) has slender metal branches (1-5-2) on both sides, and each small square metal patch (1-5-1) has a metallized via (1-5-3).

2. The microwave / millimeter-wave common-aperture antenna based on electromagnetic bandgap multiplexing with improved mutual coupling according to claim 1, characterized in that: The grounding hole (1-3), the elongated slot (1-2), and the power supply probe (1-4) are arranged sequentially from the inside to the outside of the rectangular metal patch (1-1).

3. The microwave / millimeter-wave common-aperture antenna based on electromagnetic bandgap multiplexing with improved mutual coupling according to claim 2, characterized in that: The power supply probe (1-4) passes downward through the first dielectric substrate (2), the metal ground (3), and the second dielectric substrate (4), and the bottom of the power supply probe (1-4) is connected to the metal structure of the power supply layer (5).

4. The microwave / millimeter-wave common-aperture antenna based on electromagnetic bandgap multiplexing with improved mutual coupling according to claim 3, characterized in that: The metal ground (3) has a short groove (3-1) in the area between the two small square metal patches (1-5-1).

5. The microwave / millimeter-wave common-aperture antenna based on electromagnetic bandgap multiplexing with improved mutual coupling according to claim 4, characterized in that: The top metal structure (1) has two rectangular metal patches (1-1) with a long slot (1-2) and a row of evenly distributed grounding holes (1-3) that are excited by signals fed into them through the feed probes (1-4) via port one and port two, respectively, forming two microwave planar inverted F antenna units.

6. The microwave / millimeter-wave common-aperture antenna based on electromagnetic bandgap multiplexing with improved mutual coupling according to claim 5, characterized in that: The four-element millimeter-wave antenna array (1-5) located in the middle of the top metal structure (1) consists of eight mushroom-shaped structures. Each millimeter-wave antenna array (1-5) is composed of two mushroom-shaped structures, consisting of a small square metal patch (1-5-1), a slender metal branch (1-5-2), and a metallized via (1-5-3). After the signal is fed in through an independent port, it is coupled and excited through a short slot (3-1) located in the metal ground (3).

7. The microwave / millimeter-wave common-aperture antenna based on electromagnetic bandgap multiplexing with improved mutual coupling according to claim 6, characterized in that: The elongated groove (1-2) has a length of 0.7λ in the vertical direction. g -0.75λ g , λ g The wavelength of the guided wave corresponding to the center frequency of the microwave band is 0.04λ. g -0.06λ g The distance from the grounding edge of the rectangular metal patch (1-1) is 0.3λ. g -0.35λ g In each mushroom-shaped structure, the small square metal patch (1-5-1) has a horizontal length of 0.15λ. g -0.2λ g The width is 0.08λ g -0.1λ g The slender metal dendrite (1-5-2) has a length of 0.05λ. g -0.07λ g The width is 0.015λ g -0.02λ g The diameter of the metallized via (1-5-3) is 0.013λ. g -0.015λ g The spacing between every two mushroom-shaped structures is 0.02λ. g -0.03λ g .

Images